Marker plus reader-based authentication systems can be used to distinguish authentic from counterfeit items. The authentication is based on the presence of secret markers in the authentic item and the detection of those markers with special readers. The reader responds by giving a pass/fail indication. It is important that the reader (authenticator) does not fall into unauthorized possession, because its pass/fail functionality can be exploited to manufacture a replicated security feature on the counterfeit item.
It is therefore useful to have a means of enabling the authenticator that cannot be realized by possessing the authenticator alone. Such an enabling device could be, for example, a key. However, the corresponding lock on the authentication device could give away this security mechanism and the counterfeiter would attempt to disable the lock mechanism.
It is desirable to have an enabling device to activate the authenticator separate from the authenticator itself. It is also desirable that possession of the authenticator does not make the need for an enabling device readily apparent.